NASA is holding an emergency news conference right now (not on tv). It is more than 1.5 times LARGER than Pluto and they have named it our solar system's tenth planet!

Pretty cool.

And this means now, that nine planets is history. Either we have 8 or ten+ I would say.

[This message has been edited by Ben (edited July 29, 2005).]

Robert Pearlman

NASA Scientists Discover Tenth Planet

A planet larger than Pluto has been discovered in the outlying regions of the solar system.

The planet was discovered using the Samuel Oschin Telescope at Palomar Observatory near San Diego, Calif. The discovery was announced today by planetary scientist Dr. Mike Brown of the California Institute of Technology in Pasadena, Calif., whose research is partly funded by NASA.

The planet is a typical member of the Kuiper belt, but its sheer size in relation to the nine known planets means that it can only be classified as a planet, Brown said. Currently about 97 times further from the sun than the Earth, the planet is the farthest-known object in the solar system, and the third brightest of the Kuiper belt objects.

"It will be visible with a telescope over the next six months and is currently almost directly overhead in the early-morning eastern sky, in the constellation Cetus," said Brown, who made the discovery with colleagues Chad Trujillo, of the Gemini Observatory in Mauna Kea, Hawaii, and David Rabinowitz, of Yale University, New Haven, Conn., on January 8.

Brown, Trujillo and Rabinowitz first photographed the new planet with the 48-inch Samuel Oschin Telescope on October 31, 2003. However, the object was so far away that its motion was not detected until they reanalyzed the data in January of this year. In the last seven months, the scientists have been studying the planet to better estimate its size and its motions.

"It's definitely bigger than Pluto," said Brown, who is a professor of planetary astronomy.

Scientists can infer the size of a solar system object by its brightness, just as one can infer the size of a faraway light bulb if one knows its wattage. The reflectance of the planet is not yet known. Scientists can not yet tell how much light from the sun is reflected away, but the amount of light the planet reflects puts a lower limit on its size.

"Even if it reflected 100 percent of the light reaching it, it would still be as big as Pluto," says Brown. "I'd say it's probably one and a half times the size of Pluto, but we're not sure yet of the final size.

"We are 100 percent confident that this is the first object bigger than Pluto ever found in the outer solar system," Brown added.

The size of the planet is limited by observations using NASA's Spitzer Space Telescope, which has already proved its mettle in studying the heat of dim, faint, faraway objects such as the Kuiper-belt bodies. Because Spitzer is unable to detect the new planet, the overall diameter must be less than 2,000 miles, said Brown.

A name for the new planet has been proposed by the discoverers to the International Astronomical Union, and they are awaiting the decision of this body before announcing the name.

Rob Joyner

Click on the link provided by Francis, third from the top. You'll see three photos side by side.For a slight 3D effect, look at either area between the photos and cross your eyes enough to focus.

Davide

I have found the planet in an old photographic plate taken in 1989 from the UK Schmidt Telescope. Naturally, that time it passed undiscovered.I posted an image here at http://www.skyfactory.org

Davide

DavidH

Am I the only one who thinks they're being hasty in declaring it a planet?

It's a KBO. A big KBO, but a KBO nonetheless. I wonder if we're not opening ourselves up for problems down the road by setting this precedent.

In my opinion, if its a KBO, then so is Pluto (though to be fair, I've long thought Pluto never really earned its planet distinction).

Either we declassify Pluto as a planet or Xena (as this new KBO has been unofficially named) is one, especially in light of the fact that the only consistent planet-defining quality thus far has been size.

DavidH

Personally, I wouldn't be opposed to deplanetizing Pluto.

Arguably, though, if someone wanted to keep Pluto around for sentimental reasons, you could make their argument that, unlike "Xena" (urgh), Pluto, for at least a portion of its orbit, is located within the "planetary" portion of the solar system. I'm just guessing, but I imagine bodies that share both size and proximity are going to be pretty rare.

Personally, I like the name choice of Xena, as (someone else said on another e-list) it opens us to a new genre of appropriate-sounding names that already border on classic mythology (i.e. Planet Joxer).

Names aside, can you please define the "planetary portion" of a solar system, especially as we do not have a firm understanding of planetary formation? And so Pandora's box has been opened... cats beware.

[This message has been edited by Robert Pearlman (edited August 01, 2005).]

Astro Bill

quote:Originally posted by Robert Pearlman:Personally, I like the name choice of Xena, as (someone else said on another e-list) it opens us to a new genre of appropriate-sounding names that already border on classic mythology (i.e. Planet Joxer).

Names aside, can you please define the "planetary portion" of a solar system, especially as we do not have a firm understanding of planetary formation? And so Pandora's box has been opened... cats beware.

[This message has been edited by Robert Pearlman (edited August 01, 2005).]

The recently discovered "planet" has apparently been declared to be our 10th planet by the news media because it is a good story. However, this makes SIZE the determining factor in deciding whether a new discovery is a planet. It also leaves Sedna and Quaoar in Limbo. These two discoveries in recent years started the debate about Ploto's questionable title of PLANET.

Sedna and Quaoar must be included in any debate about the definition of a planet. They are smaller than Pluto but they qualify in every other factor. If you read the link above to the prior thread, you will conclude that there is no definition of what a planet is.

In my opinion, this new discovery is so far away that it will probably never be visited by any spacecraft - in our lifetime.

[This message has been edited by Astro Bill (edited August 01, 2005).]

Robert Pearlman

quote:Originally posted by Astro Bill:The recently discovered "planet" has apparently been declared to be our 10th planet by the news media because it is a good story.

Just a small factual correction: it was NASA, rather than the media, that declared so-called "Xena" our 10th planet. You need only reference the NASA release I reprinted earlier in this thread; a release that NASA itself gave the headline, "NASA Scientists Discover Tenth Planet".

[This message has been edited by Robert Pearlman (edited August 01, 2005).]

Astro Bill

Robert:

Thanks for the clarification. However, I was referring to the many reporters who apparently just read the NASA release without considering the remifications of what they were saying. All the major networks just repeated the news release without mentioning Sedna, Quaoar, or the fact that there is no definition of a planet.

Yes, NASA may have started the discussion of a possible 10th planet because it was also good press for them in the midst of all the recent bad press. What I objected to was the absence of any mention of Sedna and Quaoar, two "new worlds" discovered in recent years in space. Where does that leave them? They should not be ignored.

If a definition of a planet is to be considered by the IAU, it must include "objects" like Sedna and Quaoar. I do not think that it would be proper or even scientific IMHO to say or even intimate that "A planet is any object in space that is the size of Pluto or bigger, among other qualifications (distance from the Sun, inclination to the other eight planets, spherical, not an asteroid or comet, etc.).

Before the discovery of "Xena", there was a brief discussion of the definition of a "planet" by scientists. But suddenly with this discovery all discussion is over and we apparently have a 10th planet as declared by NASA.

In my opinion, this "object" is too far out in space in an area that is rich in such objects. Some scientists suggest that there are 70,000 objects of various size in the Kuiper Belt. Does it make sense to call the larger ones planets and the rest KBO's or planetoids or sub-planets or monor planets?

IMHO the "planets" should end at Pluto and any other discoveries should be KBO's - Kuiper Belt Objects. Otherwise, we will someday have over 100 "planets" for children to memorize in school.

I think that it would be more appropriate to continue the discussion of the definition of a "planet" on this CollectSpace message board instead of referring members to another message board. I find the Space.com message board too difficult to use and not directly related to the collecting aspect of this hobby. What did they say there about what makes a "planet"? We should continue the discussion HERE.

DavidH

By no means was I referring anyone to the Space.com message board. cS is the only space-related message board I post on.

My link was to an article that had information about the topic that was being discussed. I find it helpful sometimes to supplement opinions with facts.

Thanks again David. I will connect to the link to Space.com to get their definition of a "Planet."

Rodina

Sure, if Pluto were discovered today, it would just be a KBO. But it wasn't, so it's grandfathered in.

That said, Pluto's only distinction is it is (or was until Xena) the largest such object. So size is the ultimate distinction. Nothing wrong with having 10 or 12 or 20 planets in the solar system, far as I'm concerned. I don't doubt in another 25 years, there will be dozens of Sedna-plus sized objects found, maybe even ones bigger than Mercury. Over time, there will come to be know three groups known as the Inner (Mer-Ven-Earth-Mars), Outer (Jup-Sat-Ur-NEp), and Distant Solar System (Pluto and KBOs).

But Pluto's a planet and always will be, just like the West Indies remain the West Indies -- and they have absolutely nothing to with India except a case of mistaken identity.